1. Field of the Invention
The present invention relates to a mobile vehicle (mobile object) having a front wheel and a rear wheel, with the front wheel being steered.
2. Description of the Related Art
As such a mobile vehicle, a motorcycle which includes a steering ratio varying means that uses a first motor to arbitrarily change the ratio of the turn angle of a handlebar manipulated by a rider to the steer angle of the front wheel, and a steering power assist means that adds auxiliary force by a second motor to the manipulation force input to the handlebar is conventionally known, as seen, for example, in Japanese Patent Application Laid-Open No. 2011-046342 (hereinafter, referred to as “Patent Literature 1”).
In the motorcycle described in Patent Literature 1, the second motor is driven on the basis of various sensor information including the steering torque, vehicle speed, engine speed, and the number of gear stages of the motorcycle, the roll, pitch, and yaw angles of the vehicle body, steered angle, and steering ratio, to assist the steering force of the front wheel. That is, control is performed to reduce the handlebar manipulation force during stopping of the motorcycle, to set the steering torque during traveling thereof, and so on.
Further, the first motor is driven on the basis of the above-described sensor information to set the steering ratio. That is, control can be performed such that the steering angle of the front wheel with respect to the handlebar manipulated variable decreases as the vehicle speed increases, and that the steering angle with respect to the handlebar manipulated variable becomes large when the rider keeps his/her balance by manipulating the handlebar while traveling at very low speeds.